Production and Modification of Cellulose Nanocrystals fromAgave tequilanaWeber Waste and Its Effect on the Melt Rheology of PLA

Soledad-Cecilia Pech-Cohuo,Jorge Uribe-Calderon,Alex Valadez-González,Victor Vladimir Amilcar Fernández-Escamilla,Gonzalo Canche-Escamilla

doi:10.1155/2018/3567901

Abstract

The production and surface modification of cellulose nanocrystals (CNC) fromAgave tequilanaWeber waste (ATW) and their effect on the melt rheology of PLA were investigated. For that, CNC were obtained from ATW residues by acid hydrolysis and grafted with 2-ethyl hexyl acrylate (2-EHA) to promote compatibility with nonpolar polymers, such as PLA. The morphology of CNC occurred as rods, spheres, and the so-called porous network observed by scanning electron microscopy (SEM) and electron transmission microscopy (TEM), and the crystallinity of the cellulose fibers was ~73% and increased up to ~94% for CNC followed by X-ray diffraction (XRD). The acid hydrolysis and alkali extraction process produce changes on the native cellulose type I from ATW bagasse resulting in a mixture of cellulose type I and II and was preserved after CNC isolation and surface grafting. Polymer grafting was assessed using Fourier-transform infrared spectroscopy (FTIR) and X-ray electron spectroscopy (XPS). Upon surface modification, the grafted CNC presented better thermal stability than CNC pristine evaluated by thermogravimetric analysis (TGA), and the surface energy of the CNC was decreased which could promote CNC dispersion within polymers. Both pristine and surface modified CNC were melt mixed with PLA to produce nanocomposites at different concentrations of CNC. Dynamic time sweep tests showed that the introduction of CNC and CNC/2-EHA decreased the complex viscosity of PLA due to polymer degradation during compounding.

Highlights

CNC have been mainly obtained by acid treatments on cellulose obtaining crystalline nanoparticles virtually free of defects [1]
The morphology of CNC occurred as rods, spheres, and the so-called porous network observed by scanning electron microscopy (SEM) and electron transmission microscopy (TEM), and the crystallinity of the cellulose fibers was ~73% and increased up to ~94% for CNC followed by X-ray diffraction (XRD)
The cellulose yield from Agave tequilana Weber waste (ATW) bagasse was 38% and for the CNC was 28% from obtained cellulose (10% from ATW bagasse); the above are similar to the study reported by Bondeson et al [1] and Hamad and Hu [25], who used similar processing conditions to those used in this study but from Picea Norway microcrystalline cellulose and commercial softwood, both were CNC cellulose type I

Summary

Introduction

CNC have been mainly obtained by acid treatments on cellulose obtaining crystalline nanoparticles virtually free of defects [1]. Surface modification of CNC is required to improve its dispersion within hydrophobic matrices and to promote adhesion at the CNC-polymer interface [12, 13]. In this sense, CNC has been grafted with. It has been reported that the use of grafted CNC (i.e., hydrophobic grafts) improved the rheological properties of the nanocomposites due to the better dispersion of CNC within the polymer matrix [22]. CNC were obtained from ATW bagasse by acid hydrolysis and surface modified with poly(2-ethyl hexyl acrylate) to produce a biodegradable reinforcer for polymer matrices [23]. The influence of CNC loading and surface modification of CNC on the complex viscosity as a function of time of PLA nanocomposites was evaluated

Experimental

Procedures

Results and Discussion

Conclusions